package panda.query.aggr;

import panda.query.scan.Scanner;
import panda.query.struct.Attribute;
import panda.query.struct.Constant;

public interface AggregateFn {
	
	/**
	 * 
	 * @param s
	 */
	public void first(Scanner s);
	
	/**
	 * 
	 * @param s
	 */
	public void next(Scanner s);
	
	/**
	 * 
	 * @return
	 */
	public Attribute getAttribute();
	
	/**
	 * 
	 * @return
	 */
	public Constant getValue();
}
